package com.hmdp.service.impl;

import cn.hutool.core.util.StrUtil;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.hmdp.dto.Result;
import com.hmdp.entity.Shop;
import com.hmdp.mapper.ShopMapper;
import com.hmdp.service.IShopService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.utils.CacheClient;
import com.hmdp.utils.SystemConstants;
import lombok.extern.slf4j.Slf4j;
import org.springframework.data.geo.Distance;
import org.springframework.data.geo.GeoResult;
import org.springframework.data.geo.GeoResults;
import org.springframework.data.redis.connection.RedisGeoCommands;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.domain.geo.GeoReference;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.Resource;

import java.util.*;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

import static com.hmdp.utils.RedisConstants.*;

/**
 * <p>
 *  服务实现类
 * </p>
 */
@Service
@Slf4j
public class ShopServiceImpl extends ServiceImpl<ShopMapper, Shop> implements IShopService {

    @Resource
    private StringRedisTemplate stringRedisTemplate;
    @Resource
    private CacheClient client;

    @Override
    public Result queryById(Long id) {
        //缓存穿透
        //Shop shop = queryWithPassThrough(id);
        //互斥锁解决缓存击穿
        //Shop shop = queryWithMutex(id);

        //互斥锁解决缓存击穿
        //Shop shop = queryWithLogicalExpire(id);


        //自定义工具类实现缓存穿透
        //Shop shop = client.queryWithPassThrough(CACHE_SHOP_KEY, id, Shop.class, this::getById, CACHE_SHOP_TTL, TimeUnit.MINUTES);

        //自定义工具类解决缓存击穿
        Shop shop = client.queryWithLogicalExpire(CACHE_SHOP_KEY, id, Shop.class, this::getById, CACHE_SHOP_TTL, TimeUnit.SECONDS);

        if (shop == null){
            return Result.fail("店铺不存在");
        }
        //7.返回
        return Result.ok(shop);
    }

    //线程池
    private static final ExecutorService CACHE_REBUILD_EXECUTOR = Executors.newFixedThreadPool(10);



    /**
     * 逻辑过期解决缓存击穿
     * @param id 店铺id
     * @return 店铺信息
     */
    /*public Shop queryWithLogicalExpire(Long id){
        String key = CACHE_SHOP_KEY + id;
        //1.从redis查询商铺缓存
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //2.判断是否存在
        if (StrUtil.isBlank(shopJson)) {
            //3.存在，直接返回
            return null;
        }

        //4.命中，需要先把json反序列化为对象
        RedisData redisData = JSONUtil.toBean(shopJson, RedisData.class);
        Shop shop = JSONUtil.toBean((JSONObject)redisData.getData(), Shop.class);
        LocalDateTime expireTime = redisData.getExpireTime();

        //5.判断是否过期
        if(expireTime.isAfter(LocalDateTime.now())){
            //5.1.未过期，直接返回店铺信息
            return shop;
        }
        //5.2.已过期，需要缓存重建
        //6.缓存重建
        //6.1.获取互斥锁
        String lockKey = LOCK_SHOP_KEY + id;
        boolean isLock = tryLock(lockKey);
        //6.2.判断是否获取
        if (isLock){
            //6.3.成功，开启独立线程(线程池)，实现缓存重建
            CACHE_REBUILD_EXECUTOR.submit(() -> {
                try {
                    //重建缓存
                    this.saveShop2Redis(id,20L);
                } catch (Exception e) {
                    throw new RuntimeException(e);
                } finally {
                    //释放锁
                    unlock(lockKey);
                }
            });
        }
        //6.4.失败，返回旧数据(过期的商铺信息)
        return shop;
    }*/


    /**
     * 解决缓存击穿，互斥锁
     * @param id id
     * @return 无
     */
    /*public Shop queryWithMutex(Long id){
        String key = CACHE_SHOP_KEY + id;
        //1.从redis查询商铺缓存
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //2.判断是否存在
        if (StrUtil.isNotBlank(shopJson)) {
            //3.存在，直接返回
            return JSONUtil.toBean(shopJson, Shop.class);
        }
        //判断命中的是否是空值
        if (shopJson != null){
            return null;
        }

        //4.实现缓存重建
        //4.1获取互斥锁
        //4.2判断是否获取成功
        Shop shop = null;
        try {
            if (!tryLock(LOCK_SHOP_KEY)){
                //4.3失败 休眠并重试
                Thread.sleep(50);
                return queryWithMutex(id);
            }

            //4.4成功根据id读数据库
            shop = getById(id);
            //5.数据库不存在，返回错误
            if(shop == null){
                // 将空值写入redis
                stringRedisTemplate.opsForValue().set(key,"",CACHE_NULL_TTL,TimeUnit.MINUTES);
                return null;
            }
            //6.数据库存在，写入redis缓存
            stringRedisTemplate.opsForValue().set(key,JSONUtil.toJsonStr(shop),CACHE_SHOP_TTL, TimeUnit.MINUTES);

        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        }finally {
            //7.释放互斥锁
            unlock(LOCK_SHOP_KEY);
        }
        return shop;
    }*/

    /**
     * 解决缓存穿透案例
     * @param id id
     * @return 无
     */
    /*public Shop queryWithPassThrough(Long id){
        String key = CACHE_SHOP_KEY + id;
        //1.从redis查询商铺缓存
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //2.判断是否存在
        if (StrUtil.isNotBlank(shopJson)) {
            //3.存在，直接返回
            return JSONUtil.toBean(shopJson, Shop.class);
        }
        //判断命中的是否是空值
        if (shopJson != null){
            return null;
        }

        //4.不存在 根据id读数据库
        Shop shop = getById(id);
        //5.数据库不存在，返回错误
        if(shop == null){
            // 将空值写入redis
            stringRedisTemplate.opsForValue().set(key,"",CACHE_NULL_TTL,TimeUnit.MINUTES);
            return null;
        }
        //6.数据库存在，写入redis缓存
        stringRedisTemplate.opsForValue().set(key,JSONUtil.toJsonStr(shop),CACHE_SHOP_TTL, TimeUnit.MINUTES);
        //7.返回
        return shop;
    }*/

    /**
     * 设置存储店铺信息逻辑过期时间并写入缓存（缓存重建）
     * @param id 店铺id
     * @param expireSeconds 逻辑过期时间
     */
    /*public void saveShop2Redis(Long id,Long expireSeconds){
        //1.查询店铺数据
        Shop shop = getById(id);
        //2.封装逻辑过期时间
        RedisData redisData = new RedisData();
        redisData.setData(shop);
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(expireSeconds));
        //3.写入redis
        stringRedisTemplate.opsForValue().set(CACHE_SHOP_KEY+id,JSONUtil.toJsonStr(redisData));
    }

    private boolean tryLock(String key){
        Boolean flag = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", 3, TimeUnit.SECONDS);
        return BooleanUtil.isTrue(flag);
    }

    private void unlock(String key){
        stringRedisTemplate.delete(key);
    }*/


    /**
     * 更新数据库 删除缓存
     * @param shop 商铺对象
     * @return 无
     */
    @Override
    @Transactional
    public Result update(Shop shop) {
        Long id = shop.getId();
        if (id == null){
            return Result.fail("店铺id不能为空");
        }
        //1.更新数据库
        updateById(shop);
        //2.删除缓存
        stringRedisTemplate.delete(CACHE_SHOP_KEY + id);

        return Result.ok();
    }

    /**
     *实现商户分页查询（根据类型分类）可以根据距离(需要前端传经纬度)
     * @param typeId 商户类型id
     * @param current 当前页码
     * @param x 经度
     * @param y 纬度
     * @return 无
     */
    @Override
    public Result queryShopByType(Integer typeId, Integer current, Double x, Double y) {
        //1.判断是否需要根据坐标查询
        if (x == null || y == null){
            //不需要坐标查，直接查数据库
            Page<Shop> page = query()
                    .eq("type_id",typeId)
                    .page(new Page<>(current, SystemConstants.DEFAULT_PAGE_SIZE));
            log.info("不需要坐标查");

            return Result.ok(page.getRecords());
        }
        //2.计算分页参数
        int from = (current - 1) * SystemConstants.DEFAULT_PAGE_SIZE;
        int end = current * SystemConstants.DEFAULT_PAGE_SIZE;

        //3.查询redis、按照距离排序、分页(这里geo分页只有limit限制查询数量没有from从哪开始查)。结果：shopId、distance
        String key = SHOP_GEO_KEY + typeId;
        log.info("x == :{}",x );
        log.info("y == {}",y);
        GeoResults<RedisGeoCommands.GeoLocation<String>> results = stringRedisTemplate.opsForGeo()
                .search(key,
                        GeoReference.fromCoordinate(x, y),
                        new Distance(999999999),
                        RedisGeoCommands.GeoSearchCommandArgs.newGeoSearchArgs().includeCoordinates().limit(end)
                );

        if (results == null){
            return Result.ok(Collections.emptyList());
        }
        //4.解析出id
        //获取results对象里的实际结果内容(因为limit，没有指定from需要手动截取从from开始的部分·逻辑分页，该list集合是0到end
        // 想要从from到end 需要截取)getContent解封装
        List<GeoResult<RedisGeoCommands.GeoLocation<String>>> list = results.getContent();
        if (list.size() <= from){
            //没有下一页了，结束
            return Result.ok(Collections.emptyList());
        }
        //4.1.截取从from ~ end的部分(用stream流不用拷贝只是跳过1节省内存空间 而list.sublist也可以截但是没stream流好)
        List<Long> ids = new ArrayList<>(list.size());
        Map<String,Distance> distanceMap = new HashMap<>(list.size());
        list.stream().skip(from).forEach(result ->{
            //4.2.获取店铺id
            String shopIdStr = result.getContent().getName();
            ids.add(Long.valueOf(shopIdStr));
            //4.3.获得距离
            Distance distance = result.getDistance();
            distanceMap.put(shopIdStr,distance);
        });

        //5.根据id查询shop
        String idStr = StrUtil.join(",", ids);
        List<Shop> shops = query().in("id", ids).last("order by field(id," + idStr + ")").list();
        for (Shop shop : shops) {
            shop.setDistance(distanceMap.get(shop.getId().toString()).getValue());
        }
        return Result.ok(shops);
    }
}
